1. Field of the Invention
The present invention relates to a piping connector preferably used in a fluid pipe in, for example, a cooling system or an intake system of an engine of an automobile.
2. Description of the Related Art
In connecting to, for example, a radiator hose or the like of an automobile, there is widely utilized a piping connector (pipe joint) made to be connected in one touch motion by only inserting a plug attached to an end portion of other pipe into a socket attached to an end portion of one pipe.
For example, in JP-A-10-9470, there is disclosed such a piping connector in which an outer peripheral groove is provided at an outer periphery of a female pipe (socket), the outer peripheral grove is provided with notched grooves penetrating inner and outer diameters and opposed to each other by a necessary angle, a stop piece arm (stopper) is engaged with a valley peripheral diameter portion of an unnotched groove portion, respective locking arms extended from the stop piece arm are made to span the respective notched grooves to lock, and portions of the respective locking arms are projected into the female pipe and fit to a groove at an outer periphery of a male pipe (plug).
Such a piping connector is arranged with a seal ring between an inner periphery of the socket and an outer periphery of the plug in order to seal in airtight such that a fluid flowing at inside of a pipe does not leak in a state of connecting the connector.
The seal ring is mounted to a ring-like groove portion constituted by a ring-like stepped portion provided on a depth side of the socket and a hold ring provided on a side of an opening portion at a predetermined interval from the stepped portion. The hold ring is fixedly attached to the inner periphery of the socket by a method of fitting, press-fit or the like.
However, according to the method of fixedly attaching the hold ring to the inner periphery of the socket by fitting or press-fit, when a fluid at high temperature and high pressure is made to flow to inside of the connected pipe, there is a concern that the hold ring is detached by loosening fitting or press-fit.
Further, although it is also considerable to weld the hold ring to the inner periphery of the socket, particularly in the case of ultrasonic welding, a molten resin is extruded from a weld face to produce burrs and therefore, there is a concern that the burrs are brought into contact with the seal ring to damage the seal ring.